<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <style>
        body{
            margin: 0;
            padding: 0;
            background-image: url("https://timgsa.baidu.com/timg?image&quality=80&size=b9999_10000&sec=1487328741651&di=d8208e5ecba924b32f0dee2541c0d837&imgtype=0&src=http%3A%2F%2Fimg.zcool.cn%2Fcommunity%2F01e60e56e7aa8f32f875520fa93b49.jpg");
            background-position: center center;
            background-repeat: no-repeat;
            background-size: 100px;
            height: 600px;
            background-attachment: fixed;
        }
        #div01{
            width: 400px;
            height: 200px;
            background-color: grey;
            /*margin: auto;*/
            /*margin-top: 25%;*/
            position: relative;


        }
        #div02{
            color:blue;
            height: 100px;
            width: 50%;
            background-color: #41ffa2;
            /*margin-top: 25%;*/
            position: absolute;
            border: dotted 10px red;


        }

    </style>
</head>
<body>
    <div id="div01">
        <div id="div02">
            hello
        </div>
    </div>


</body>
</html>